Treatment of heavy petroleum oils

ABSTRACT

ASPHALTENES AND METALS ARE REMOVED FROM HEAVY PETROLEUM OILS BY DISPERSING THE OIL IN STEAM AT A TEMPRATURE OF AT LEAST 750*F. THEN COOLING TO FORM A STABLE WATRASPHALTENE EMULSION. AFTER SEPARATION FROM THE EMULSION, THE TREATED OIL MAY BE USED AS A FUEL OR SUBJECTED TO HYDROCONVERSION.

United States Patent cc 3 733 259 TREATMENT OF nEAvY PETROLEUM orLs Raymond F. Wilson, Edward L. Cole, and Reese A. Peck, 1l\ Tisl(1kill, N.Y., assignors to Texaco Inc., New York,

No Drawing. Filed Nov. 10, 1971, Ser. No. 197,364

Int. Cl. Cg 31/08 US. Cl. 208-86 10 Claims ABSTRACT OF THE DISCLOSURE TREATMENT OF HEAVY PETROLEUM OILS This invention is concerned with the treatment of heavy petroleum oils. More particularly it is concerned with the removal of contaminants from residue-containing oils. In one of its more specific aspects it is concerned with the removal of metals, asphaltenes and sulfur from heavy hydrocarbon oils.

In the refining of petroleum it is conventional to distill a crude oil to remove valuable lighter boiling fractions such as naphtha, kerosine and light and heavy gas oils. The still residue is a heavy oil containing higher boiling hydrocarbons and is contaminated with asphaltenes and compounds containing sulfur, nitrogen and metals which make such an oil undesirable as a fuel. In order to remove the sulfur or nitrogen or to convert the heavy residue into lighter more valuable products, the oil is ordinarily subjected to a hydro-catalytic treatment. This is conventionally done by contacting the oil with hydrogen at elevated temperature and pressure with a particulate catalyst. Unfortunately, unlike distillate stocks which are substantially free from asphaltenes and metals, the presence of asphaltenes and metal-containing compounds in the heavy oil leads to a relatively rapid reduction in the activity of the catalyst to below a practical level. The presence of these materials in the charge stock results in the deposition of metal-containing coke on the catalyst particles which prevents the charge from coming in contact with the catalyst and thereby, in effect, reduces the catalyst activity. Eventually, the on-sream period must be interrupted and the catalyst regenerated.

Regeneration of the catalyst is accomplished by sweeping the reaction zone with an inert gas to remove combustible vapors and then introducing an oxygen-containing gas under carefully controlled conditions to oxidize the deposited carbon or coke without subjecting the catalyst to extremely high temperatures. This treatment results in the removal of the carbon deposit from the surface of the catalyst, and the on-stream period may be resmued with a catalyst of restored activity. However, the metals deposited on the catalyst are not removed by the combustion and gradually the metal build-up on the catalyst is sufficient to deactivate the catalyst to an unsatisfactory level. When this stage is reached the catalyst activity cannot be restored by ordinary methods and it becomes necessary to remove the catalyst from the reaction zone and replace it with fresh catalyst.

It is therefore an object of this invention to remove asphaltenes and metal containing compounds from heavy petroleum oils. Another object is to convert heavy petroleum oils into more valuable products such as low sulfur fuel oils and/or lighter products. Another object is to pro- 3,733,259 Patented May 15,, 1973 long the on-stream periods of hydro-catalytic treatment of heavy petroleum oils. These and other objects will be obvious to those skilled in the art from the following disclosure.

According to our invention, there is provided a process for the catalytic hydroconversion of a heavy petroleum oil containing sulfur, asphaltenes and metals which comprises forming a dispersion of said oil with H 0, maintaining said dispersion at a temperature between 750 and 850 F. and a pressure between atmospheric and p.s.i.g. for at least one-half hour, cooling said dispersion to form a stable water-asphaltene emulsion, separating the emulsion from the treated oil and contacting the resulting treated oil with a hydrogenation catalyst in the presence of added hydrogen at a temperature between 500 and 900 F. and a pressure between about 300 and 3,000 p.s.i.g.

The charge stocks used in the process of this invention are residue-containing oils such as crude petroleum oils, atmospheric residua, vacuum residue, shale oil, tar sand oil and the like, of which asphaltenes and metal-containing compounds comprise a significant portion.

The charge stock is contacted with water at a temperature of at least 750 F. preferably 750 to 850 F. since, above about 850 F. some coke formation takes place. The pressure may be atmospheric or super atmospheric for example up to about 100 p.s.i.g. The oil and water (steam) are passed through a zone wherein they come into intimate contact to form an oil-steam dispersion. The reaction zone may be either in the form of an elongated tubular zone through which the reactants are passed under conditions of turbulent flow or it may be in the form of a vessel filled with an inert packing such as glass beads or Berl saddles. The reaction mixture is heated to a temperature above 750 F. and maintained at that temperature for at least about one half-hour preferably from 1-2 hours so that upon cooling a stable waterasphaltene emulsion is formed. The emulsion, which has a grease-like consistency, may be separated from the treated oil by filtration, sedimentation or decantation and the treated oil may then be subjected to stripping to remove residual traces of water. If desired the emulsion may be dried and metals recovered therefrom. The treated oil may be used as a fuel of low metal content or may be subjected to further processing as by hydro-catalytic treatment such as hydro-desulfurization or hydrocracking.

The hydro-catalytic treatment of the treated oil, which may be either a hydro-desulfurization or a hydrocracking, is carried out by contacting the treated oil in the presence of added hydrogen with a catalyst at elevated temperature and pressure. Reaction conditions include temperatures between about 500 and 900 F. and pressures between about 300 and 3,000 p.s.i.g. Preferred temperatures are from about 650 to 850 F. and preferred pressures range from about 500 to 1500 p.s.ig. The oil may be passed through the reaction zone at a space velocity between about 0.2 and 5.0 volumes of oil per volume of catalyst per hour, preferably between about 0.5 and 2 v./v./hr. with a hydrogen rate of between about 500 and 10,000 standard cubic feet per barrel of oil preferably between about 750 and 5000 s.c.f.b.

The catalyst may be used as a slurry or in the form of a fixed bed, a fluidized bed or a moving bed and the reacant stream may be passed upwardly or downwardly through the reaction zone. Preferably the catalyst is in the form of a fixed bed of pellets, and the reactant stream is passed downwardly through the catalyst bed.

The hydro converison catalyst generally will comprise a group VI-B metal and a group VIII metal usually as the oxide on a support. When the principle hydro-conversion reaction is desulfurization the catalyst support comprises a refractory inorganic oxide such as alumina, magnesia, or zirconia, or mixtures thereof. Small, e.g., less than stabilizing amounts of silica may be present. If the principal hydro-conversion reaction is hydrocracking the base or support will have cracking activity. Suitable supports comprise silica and alumina mixtures containing at least about 50% silica. The hydrocracking catalyst may also contain a modified zeolite such as faujasite or zeolite Y which has been subjected to a decatoinization treatment for the removal of alkali metal ion and the introduction into the zeolite structure of hydrogen ion. Advantageously the alkali metal is removed by subjecting the zeolite to ion exchanger with a solution of an ammonium compound followed by heating to dry and then calcination. The calcined zeolite is subjected to a second ion exchange with a solution of an ammonium compound and then dried. This treatment results in a zeolite having an alkali metal content of less than about 1 percent by weight.

The hydro conversion catalyst should contain between about 2 and 10 percent by weight of the group VI-B metal and between about 5 and 40 percent by weight of the group VIII metal. Suitable combinations are nickel and molybdenum nickel and tungsten and cobalt and molybdenum. A particularly suitable catalyst for the hydrocracking of a treated oil which contains more than 100 parts per million nitrogen comprises 3 to 8 percent nickel, to 30 percent tungsten on a support comprising to percent decationized zeolite Y, 50 to 75 percent silica and 5 to 20 percent alumina. Advantageously, the catalyst is sulfided prior to use.

The hydrogen used in this process need not necessarily be pure. Satisfactory results are obtained using hydrogen of at least 60 percent purity. Preferably the hydrogen purity is between about 70 and 95 percent by volume. Suitable sources of hydrogen are catalytic reformer by product hyrogen, electrolytic hydrogen or hydrogen prepared by the partial oxidation of a hydrocarbon material followed by shift conversion and CO removal.

The following examples are given for illustrative purposes only.

EXAMPLE I This example shows the catalytic hydrodesulfurization of an untreated charge. The charge stock is a Lago Medio atmospheric reduced crude having the characteristics described in Table I.

TABLE I Gravity, API 19.9 Conradson carbon residue, wt. percent 6.89 Sulfur, wt. percent 2.0 Asphaltenes, wt. percent 2.94 Nickel, p.p.m. 20 Vanadium, p.p.m. 215 Nitrogen, wt. percent 0.27

500 grams of the charge and 50 grams of a pelleted catalyst composed of 2 percent nickel, and 13.5 percent molybdenum as the oxides on alumina containing 3 percent silica is charged to a rocking autoclave, pressured to 500 p.s.i.g. with hydrogen and held at 725 F. for 2 hours. The total weight of the oil and catalyst recovered is 545 grams. The catalyst is separated from the oil and is found to be covered with a heavy layer of coke-like material. The oil has the analysis described in Table II below:

TABLE II Conradson carbon residue, wt. percent 4.85 Sulfur, wt. percent 1.03 Nickel, p.p.m. 21 Vanadium, p.p.m. 139

EXAMPLE II This example is directed to water treatment followed by catalytic hydrodesulfurization without intermediate removal of the asphaltene-water emulsion. The same charge TABLE III Temperature, F 800 725 Pressure, p.s.i.g 0 500 Space velocity, oil v./v./hr 1.00 Space velocity, water, v./v./hr 0.33

Product quality, oil:

Sulfur, wt. percent 0.85 Conradson carbon residue, wt. pcreci 4. 36 Asphaltencs, wt. Dercnt. 2. 14 Niekes, p.p.m 11 Vanadium, p.p.m. 89

EXAMPLE III This example is representative of the process of our invention. The first stage of Example II is repeated and after the water (steam) treatment, the product is cooled with formation of a stable water-asphaltene emulsion having a grease-like consistency. The emulsion is separated from the treated oil by filtration, the treated oil is then stripped to remove traces of H 0 and hydrogenated in a second stage as in Example I. Data on the reaction conditions, the product oil and the dried emulsion are set forth in Table IV, Column A listing data from the first stage and Column B data from the second stage.

Visual inspection shows the catalyst to be essentially free from deposits.

EXAMPLE IV This example shows the importance of temperature during the water (steam) treatment. Data for three runs the same as the first stage of Example II with the exception of temperature in Runs A and B are tabulated below.

TABLE V Run A B 0 Temperature, "F 600 700 800 Pressure, p.s.i.g 0 0 0 Space velocity of oil, v./v./hr 1.0 1.0 1.0 Space velocity water, v./v.lhr 0.33 0.33 0.33 Stable emulsion, dried \vt. percent basis charge. None None 5. 3

These results show that at a temperature of 600 or 700 F. the treatment with water or steam does not result in the formation of a stable emulsion on the cooling of the product of the water treatment. The results also show that the process of this invention can be used to improve residual oil hydroconversion to yield a product that is lower in sulfur, carbon residue, and asphaltenes. They also show that a lower sulfur level can be obtained when the oil is treated with Water at a temperature above 750 F. instead of being subjected directly to hydroconversion. It will also be noted that filtration of the product of the Water treatment produces a product with a lower carbon residue, metal and asphaltene content.

Various other modifications of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A process for the catalytic hydroconversion of a heavy petroleum oil containing sulfur, asphaltenes and metals which comprises forming a dispersion of said oil with H O, maintaining said dispersion at a temperature between 750 and 850 F. and a pressure between atmospheric and 100 p.s.i.g. for at least one half hour, cooling said dispersion to form a stable water-asphaltene emulssion, separating the emulsion from the treated oil and contacting the resulting treated oil with a hydrogenation catalyst in the presence of added hydrogen at a temperature between 500 and 900 F. and a pressure between about 300 and 3,000 p.s.i.g.

2. The process of claim 1 in which the H oil weight ratio is between 0.33 and 1.

3. The process of claim 1 in which the H O-oil dispersion is maintained at a temperature between 775 and 850 F.

4. The process of claim 1 in which the dispersion is maintained at 750-850 F. for 0.5-2 hours.

5. The process of claim 1 in which the hydrogenation catalyst is a hydrodesulfurization catalyst.

6. The process of claim 1 in which the hydrogenation catalyst is a hydrocracking catalyst.

7. The process of claim 1 in which the hydrogenation catalyst comprises a compound of a Group VI-B metal and a compound of a Group VIII metal.

8. The process of claim 1 in which the separation is efiected by filtration.

9. The process of claim 1 in which the separation is effected by decantation.

10. The process of claim 1 in which the separation is effected by sedimentation.

References Cited UNITED STATES PATENTS 2,789,083 4/1957 Hardy 2'0825 1 R 2,825,678 3/1958 Jahnig et a1. 208-25l R 3,294,678 12/1966 Gleim 208-309 HERBERT LEVINE, Primary Examiner US. Cl. X.R. 208-25 1, 309 

